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compiler-rt: fix signed min int from float

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Jacob Young 2025-03-08 01:42:03 -05:00 • committed by Andrew Kelley
parent 7e0c25eccd
commit a5900e310e
2 changed files with 44 additions and 2 deletions
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6
lib/compiler_rt/int_from_float.zig
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@ -72,10 +72,12 @@ pub inline fn bigIntFromFloat(comptime signedness: std.builtin.Signedness, resul
} }); } });
const parts = math.frexp(a); const parts = math.frexp(a);
const exponent = @max(parts.exponent - significand_bits, 0); const significand_bits_adjusted_to_handle_smin = @as(i32, significand_bits) +
@intFromBool(signedness == .signed and parts.exponent == 32 * result.len);
const exponent = @max(parts.exponent - significand_bits_adjusted_to_handle_smin, 0);
const int: I = @intFromFloat(switch (exponent) { const int: I = @intFromFloat(switch (exponent) {
0 => a, 0 => a,
else => math.ldexp(parts.significand, significand_bits), else => math.ldexp(parts.significand, significand_bits_adjusted_to_handle_smin),
}); });
switch (signedness) { switch (signedness) {
.signed => { .signed => {

40
lib/compiler_rt/int_from_float_test.zig
View file

@ -24,6 +24,8 @@ const __fixdfdi = @import("fixdfdi.zig").__fixdfdi;
const __fixunsdfdi = @import("fixunsdfdi.zig").__fixunsdfdi; const __fixunsdfdi = @import("fixunsdfdi.zig").__fixunsdfdi;
const __fixdfti = @import("fixdfti.zig").__fixdfti; const __fixdfti = @import("fixdfti.zig").__fixdfti;
const __fixunsdfti = @import("fixunsdfti.zig").__fixunsdfti; const __fixunsdfti = @import("fixunsdfti.zig").__fixunsdfti;
const __fixdfei = @import("fixdfei.zig").__fixdfei;
const __fixunsdfei = @import("fixunsdfei.zig").__fixunsdfei;
// Conversion from f128 // Conversion from f128
const __fixtfsi = @import("fixtfsi.zig").__fixtfsi; const __fixtfsi = @import("fixtfsi.zig").__fixtfsi;
@ -681,6 +683,44 @@ test "fixunsdfti" {
try test__fixunsdfti(-0x1.FFFFFFFFFFFFEp+62, 0); try test__fixunsdfti(-0x1.FFFFFFFFFFFFEp+62, 0);
} }
fn test_fixdfei(comptime T: type, expected: T, a: f64) !void {
const int = @typeInfo(T).int;
var expected_buf: [@divExact(int.bits, 32)]u32 = undefined;
std.mem.writeInt(T, std.mem.asBytes(&expected_buf), expected, endian);
var actual_buf: [@divExact(int.bits, 32)]u32 = undefined;
_ = switch (int.signedness) {
.signed => __fixdfei,
.unsigned => __fixunsdfei,
}(&actual_buf, int.bits, a);
try testing.expect(std.mem.eql(u32, &expected_buf, &actual_buf));
}
test "fixdfei" {
try test_fixdfei(i256, -1 << 255, -0x1p255);
try test_fixdfei(i256, -1 << 127, -0x1p127);
try test_fixdfei(i256, -1 << 100, -0x1p100);
try test_fixdfei(i256, -1 << 50, -0x1p50);
try test_fixdfei(i256, -1 << 1, -0x1p1);
try test_fixdfei(i256, -1 << 0, -0x1p0);
try test_fixdfei(i256, 0, 0);
try test_fixdfei(i256, 1 << 0, 0x1p0);
try test_fixdfei(i256, 1 << 1, 0x1p1);
try test_fixdfei(i256, 1 << 50, 0x1p50);
try test_fixdfei(i256, 1 << 100, 0x1p100);
try test_fixdfei(i256, 1 << 127, 0x1p127);
try test_fixdfei(i256, 1 << 254, 0x1p254);
}
test "fixundfei" {
try test_fixdfei(u256, 0, 0);
try test_fixdfei(u256, 1 << 0, 0x1p0);
try test_fixdfei(u256, 1 << 1, 0x1p1);
try test_fixdfei(u256, 1 << 50, 0x1p50);
try test_fixdfei(u256, 1 << 100, 0x1p100);
try test_fixdfei(u256, 1 << 127, 0x1p127);
try test_fixdfei(u256, 1 << 255, 0x1p255);
}
fn test__fixtfsi(a: f128, expected: i32) !void { fn test__fixtfsi(a: f128, expected: i32) !void {
const x = __fixtfsi(a); const x = __fixtfsi(a);
try testing.expect(x == expected); try testing.expect(x == expected);